Suppose you are interested in estimating the effect of hours spent per week studying (STUDY) on university grade point average (GPA) for university students. GPA = beta0 + beta1 STUDY + u (i) Suggest a possible omitted variable. What is the correlation between the regressor and the omitted variable? [0.5 marks] (ii) What is the likely sign of the effect of the omitted variable and the dependent variable? [0.5 marks] (iii) Speculate as to whether the OLS estimator of the slope coefficient will be upward or downward biased due to this omitted variable. Make sure to justify your assessment. [0.5 marks]